1. Field of the Invention
The present invention relates to a truck cab assembly and more specifically provides for a modular assembly of a cab extension, such as used for cab sleepers, which simplifies construction of a flared aerodynamic body for the extension using carry over parts from a straight body sleeper.
2. Description of the Problem
Long haul trucking plays a major role in North American shipping. For reasons of economy and convenience, long haul truck tractors are provided with sleepers, semi-enclosed sections of the vehicle cabs extending behind the operator section of the cab. Sleepers typically include one or more bunks for sleeping, and amenities such as tables, chairs, storage closets and the like. Living space is at a premium in these sections, in part because the permissible length of the compartments is severely limited by legal limitations on the overall length of vehicles and the need to protect the swing clearance area for a trailer attached to the truck tractor""s fifth wheel. Some additional space can be obtained by widening the sleeping section compared to the operator section of the cab. Vehicle aerodynamic properties are improved if the transition between the relatively narrow operator section of the cab and the wider sleeper section is smooth and tapered. Such extended cabs are called flared sleepers.
The construction of an extended cab which varies in width along its length presents challenges both from a cost perspective and from the perspective of maintaining a good fit between components. For example, gaps of even width between doors and door pillars are widely perceived as a mark of good workmanship. Conventionally, an extended, flared sleeper cab is built on a underbody module, which forms the floor of the cabin. The floor of the underbody module has curved longitudinal edges matching the cross sectional shape of the cabin flare. Incorporating a flare into the underbody can result in manufacturing problems including problems relating to the positioning of machinery in the production line. The manufacture of underbodies of differing widths may also require different tooling to produce the different underbodies.
It would be desirable to provide a truck body with a flared, extended cab which can be constructed using as many as possible of the same core body components used in a straight wall truck cab and allowing much of the same production machinery to be used for assembly.
It would be further desirable to provide a flare cab truck body constructed in modules, with a minimum of additional components compared with a straight wall truck cab.
According to the invention there is provided a truck cab having a forward operator section and an aft living unit. The aft living unit is defined by an underbody providing a central floor area, left side and right side flare modules providing longitudinal side walls, outer portions of the floor and outer portions of the back wall, and a center back wall section between the outer portions of the back wall formed by the flare sections. The longitudinal side wall narrow on one another forward from the back wall and the outer floor portions narrow from rear to front.
The underbody has straight longitudinal sides and is adapted for mounting on a vehicle chassis. The left and right side flare modules are positioned along opposite longitudinal sides of the underbody, the side flare modules each comprising, a flare side assembly, a rear side floor panel mounted along and perpendicular to a bottom edge of the flare side assembly and backwall extensions. The underbody and first and second side flare modules are joined along a fore/aft slip joint defined along adjacent edges of the rear side floor panels and the underbody. The back wall assembly is centered between the back wall panel extensions of the flare side assemblies and is joined to those assemblies along vertical slip joints. The aft living unit is joined to the forward operator section along the sides by pillars.
Additional effects, features and advantages will be apparent in the written description that follows.